Pomodoro stop button

Good evening to all the great people on this platform. I’m currently working on a front-end pomodoro clock and I’m having trouble on how to stop the clock. If anybody can donate some of their time to help me hook up the stop button. I’m using the clearInterval() function once it reaches 0 but I’m lost in how to stop the clock at any given moment. I’ve tried using an if statement in the scope of the current function but it doesn’t work. hers is my link to Codepen: https://codepen.io/alexbuster/pen/qBXeBmY